A Credit-Based Incentive Protocol for Stimulating Network-Coded Cooperative Content Distribution in VANET

As the high-speed vehicular node passes the coverage area of a road side unit in the vehicular ad hoc network, it may not be able to receive all content information broadcast by the RSU during the short contact duration with the RSU. Hence, when the vehicular node leaves the coverage area of the RSU, it has to adopt the cooperative content distribution approach to share its received content pieces, which are encoded by the network coding technology, with all neighboring nodes. However, these approaches do not consider that vehicular nodes in reality may have different degrees of selfishness and interests on various types of content information, which in turn hinders those selfish nodes from sharing their contents with others. In this paper, we will propose the Social Code scheme, adopting the content bitmap, for each node to calculate the number of different network-coded content pieces, its corresponding re-broadcast priority and the correct number of re-encoded NC content pieces with all neighbor nodes first. Social Code then classifies vehicular nodes into four types and further integrates corresponding credit-based incentive protocols to stimulate nodes' willingness to re-broadcast their content pieces. Finally simulation results show that Social Code outperforms over traditional NC-based cooperative content distribution schemes, if they adopt the credit-based incentive protocols without considering node selfishness and interests.